Would three BMPs at low concentration be better than one at high concentration? An experimental study with rat osteoprogenitor cells.

Background: Bone morphogenetic proteins (BMPs) are used in clinical practice for stimulation of bone formation, but often evoke serious complications. Recent studies demonstrated that BMPs involved in early stages of bone formation are species specific. In cattle dominate BMP7, growth differentiation factor 5 (GDF5) and NEL-like protein 1 (NELL1) while in rats BMP2, BMP5 and BMP6.

Toward osteomimetic formation of calcium phosphate coatings with carbonated hydroxyapatite.

Biomimetic production of coatings on various types of scaffolds is based mainly on simulated body fluid precipitation (SBF) of apatites, or, if the HCO is present, carbonated apatites. Recently, we proposed formation of calcium phosphates (CaP) precipitates by alkaline phosphatase (ALP) hydrolysing glycerophosphate in presence of calcium ions as an alternative to SBF. Since apatites synthesized in bone by the ALP activity contain carbonate anions, it was tempting to investigate whether the phosphatase method could be advanced into osteomimetic one.

Could BMPs Therapy Be Improved if BMPs Were Used in Composition Acting during Bone Formation in Endochondral Ossification?

The discovery of bone morphogenetic proteins (BMPs) inspired hope for the successful treatment of bone disorders, but side effects worsening the clinical effects were eventually observed. BMPs exert a synergistic effect, stimulating osteogenesis; however, predicting the best composition of growth factors for use in humans is difficult. Chondrocytes present within the growth plate produce growth factors stored in calcified cartilage adhering to metaphysis.

Growth factors in the initial stage of bone formation, analysis of their expression in chondrocytes from epiphyseal cartilage of rat costochondral junction.

Introduction: In endochondral ossification septoclasts and osteoclasts (also called chondroclasts) release growth factors deposited in non-calcified and calcified zones of the growth plate. They stimulate, within the metaphysis, initial stages of the bone formation. We have recently reported quantitation of several growth factors in calcified cartilage from calf costochondral junction.

Growth factor profile in calcified cartilage from the metaphysis of a calf costochondral junction, the site of initial bone formation.

Endochondral bone formation is orchestrated by growth factors produced by chondrocytes and deposited in the cartilage matrix. Whilst some of these factors have been identified, the complete list and their relationship remains unknown. In the present study, the growth factors were isolated from non-calcified and calcified cartilage of costochondral junctions.

From Matrix Vesicles to Miniature Rocks: Evolution of Calcium Deposits in Calf Costochondral Junctions.

Objective: Initial stages of cartilage matrix calcification depend on the activity of matrix vesicles. The purpose of the study was to describe how calcified matrix vesicles join into larger structures, to present their up-to-date undescribed 3-dimensional image, and to observe how calcified matrix relates to chondrocyte lacunae.

Design: Calcified cartilage was obtained from the zone of provisional calcification of calf costochondral junctions, then enzymatically isolated and studied by microtomography, scanning electron microscopy, atomic force microscopy and X-ray diffraction, and Fourier transform infrared spectroscopy.

The solid-state proton NMR study of bone using a dipolar filter: apatite hydroxyl content animal age.

The hydroxyl content of bone apatite mineral has been measured using proton solid-state NMR performed with a multiple-pulse dipolar filter under slow magic angle spinning (MAS). This new method succeeded in resolving and relatively enhancing the main hydroxyl peak at 0 ppm from whole bone, making it amenable to rigorous quantitative analysis. The proposed methodology, involving line fitting, the measurement of the apatite concentration in the studied material and adequate calibration, was proved to be convenient and suitable for monitoring bone mineral hydroxylation in different species and over the lifetime of the animal.

Formation of calcium phosphate coatings within polycaprolactone scaffolds by simple, alkaline phosphatase based method.

The paper presents a novel approach to the production of calcium phosphate coatings of scaffolds. Mineral deposits were formed during incubation of polycaprolactone (PCL) scaffolds with bovine intestinal alkaline phosphatase in sodium glycerophosphate and calcium chloride medium. To modify hydrophobic surface of scaffolds and intensify attachment of coating, scaffolds were incubated at 50 °C (thermal activation, TA) or at 37 °C after short exposition to lipase (lipase activation, LA).

Influence of cartilage interstitial fluid on gene expression in cruciate ligament fibroblasts.

Loading of articular cartilage during motion squeezes the fluid from the cartilage, termed cartilage interstitial fluid (CIF), which was found to influence gene expression in synovial membrane cells. After crucial ligaments damage, these cells are exposed to synovial fluid containing factors released from articular cartilage; the aim of the present study was to establish the influence of CIF and factors present in CIF (CIF-like cocktails) on crucial ligament fibroblasts. CIF was squeezed from articular-epiphyseal cartilage complexes of newborn rats.

Influence of IGF1, TGFβ1, bFGF and G-CSF/M-CSF on the mRNA levels of selected matrix proteins, cytokines, metalloproteinase 3 and TIMP1 in rat synovial membrane cells.

Introduction: We have previously observed that rat synovial membranes incubated in medium containing cartilage interstitial fluid (CIF) responded by changes in the expression of hyaluronan synthases (HAS1 and HAS2), collagen type I, versican, aggrecan, lubricin, matrix metalloproteinases 2 and 3 (MMP2 and MMP3), tissue inhibitors of metalloproteinases (TIMP1, 2 and 3), transforming growth factor β1 (TGFβ1), tumor necrosis factor (TNF), interleukin (IL) 1β and IL-6. The aim of the study was to evaluate the influence of particular cytokines found in CIF on the gene expression of extracellular matrix (ECM) proteins in synovial membrane cells.

Material And Methods: Synovial membranes (SMs) were removed from the knee joints of inbred, male Lewis rats and incubated with insulin-like growth factor 1 (IGF1), TGFβ1, basic fibroblast growth factor (bFGF) and granulocyte- macrophage colony-stimulating factors (G-CSF and M-CSF), either individually or in the combinations TGFβ1/IGF1, TGFβ1/IGF1/bFGF or G-CSF/M-CSF.

Influence of cartilage interstitial fluid on the mRNA levels of matrix proteins, cytokines, metalloproteases and their inhibitors in synovial membrane.

Articular cartilage and the synovial membrane both ensure the smooth action of synovial joints; however, the influence of chondrocytes on synovial metabolism remains unclear. The secretory activity of chondrocytes is usually studied in cell cultures and may differ from that in intact cartilage. According to McCutchen's theory of 'weeping' joint lubrication, loading of the articular cartilage during motion squeezes the fluid with lubricating properties from the cartilage.

Insight into characteristic features of cartilage growth plate as a physiological template for bone formation.

Cartilage growth plate is a natural template from both a biochemical and structural point of view and allows osteoblasts migration, proliferation, differentiation, and ultimately, bone formation. It is evolutionary adjusted to support bone formation within strictly defined spatial framework serving as an interesting model for studying more mechanistically aspects which might be important for specific scaffold-based bone tissue engineering strategies. Surprisingly little is known about the geometric features of this physiological template.

Synovial membrane asks for independence.

Synovial membrane is traditionally considered as a part of the joint capsule. It, however, differs from fibrous part of the capsule in development, structure, function, vascularisation, innervation and involvement in pathological processes. Moreover, in some areas, it even does not contact with the fibrous capsule.

Rat chondrocyte-associated antigen identified as sialylated transmembrane protein Tmp21 belonging to the p24 protein family.

Rabbit serum produced after transplantation of isolated rat chondrocytes [sensitized rabbit serum (SRS)] demonstrated M r ~ 74- and ~23-kDa (western blot analysis) antigens in rat chondrocyte extracts. Only the latter remained after reduction in 2-mercaptoethanol. Protein sequence analysis of 23-kDa chondrocyte-associated antigen (CAA) revealed that it corresponds to transmembrane Tmp21 protein belonging to the p24 protein family.

Formation of synovial joints and articular cartilage.

Chondrocytes differentiate from mesenchymal progenitors and produce templates(anlagen) for the developing bones. Chondrocyte differentiation is controlled by Sox transcription factors. Templates for the neighbour bones are subsequently separated by conversion of differentiated chondrocytes into non-chondrogenic cells and emergence of interzone in which joints cavitation occurs.

Hydrostatic and boundary lubrication of joints--nature of boundary lubricant.

A very low coefficient of friction in joints makes it difficult to define clearly the mechanism of cartilage lubrication. The present paper describes the two currently predominant and mutually complementary views aiming to elucidate this mechanism. The first mechanism, referred to as hydrostatic lubrication, involves interstitial fluid pressurization from the cartilage and its importance for the formation of a layer separating the weight-bearing surfaces.

Involucrin, but not filaggrin and Kdap mRNA, expression is downregulated in 3-D cultures of intact rat hair bulbs after calcium stimulation.

The hair follicle consists of several distinctive epidermal cell layers. The hair root, which undergoes keratinization, is surrounded by two sheaths: the inner root sheath (IRS) and the outer root sheath (ORS). The ORS is continuous with the basal layer of the epidermis.

Fecal lactoferrin and Clostridium spp. in stools of autistic children.

Stools from autistic and healthy children were studied for fecal lactoferrin, Clostridium difficile toxins, Clostridium perfringens enterotoxin and cultured for Clostridium spp. Elevated level of FLA was demonstrated in 24.4% stools, all from boys (31.

Influence of LPS, TNF, TGF-ß1 and IL-4 on the expression of MMPs, TIMPs and selected cytokines in rat synovial membranes incubated in vitro.

Synovial membranes are formed by four main types of cells, i.e. fibroblasts, macrophages, epitheliocytes and adipocytes.

Pro- and anti-inflammatory cytokines increase hyaluronan production by rat synovial membrane in vitro.

Synovial membrane consists of fibroblasts and macrophages forming the synovial lining supported by vascularized subsynovium. Each of these components may specifically react to a particular stimulus. Thus, reactions of isolated synovial cells may not correspond to that of intact tissue.

Chondrocyte-associated antigen and matrix components in a 2- and 3-dimensional culture of rat chondrocytes.

The goal of this study was to compare expression of chondrocyte-associated antigen (CAA) and cartilage matrix molecules in 2-D (monolayer) and 3-D (Matrigel) culture. Chondrocytes isolated from the cartilage of 3-day-old rats were expanded in monolayer culture for 28 days. CAA expression gradually decreased and was not detected beyond the 96th hour of monolayer culture.

Keratinization of outer root sheath cells is prevented by contact with inner root sheath of rat hair follicles.

The purpose of the present study was to elucidate why keratinocytes of the outer root sheath (ORS) do not keratinize in situ. Two possibilities were considered--inhibition of keratinization is caused by contact of ORS with inner root sheath (IRS) or insufficient supply of keratinization promoting factors from the surrounding tissues to the ORS. In order to distinguish between these possibilities mid-segments of hair follicles were liberated from the dermis by dissection followed by collagenase digestion.

The morphology and selected biological properties of articular cartilage.

The purpose of this article is to present the current state of knowledge regarding the structure and functions of articular cartilage. Articular cartilage is constructed with hyaline cartilage tissue. It is composed of chondrocytes located in lacunae and the extracellular matrix.